Solar System Log by Andrew Wilson, published 1987 by Jane's Publishing Co. Ltd.

NASA initially conceived of the Surveyor program as a landing and orbiting robotic lunar project, but it scaled down plans to a more specific program of 10 lunar soft-landers (7 were eventually launched) geared toward basic engineering goals rather than scientific exploration.

The primary scientific instrument was an imaging system. Unlike the Soviet Luna landers, Surveyor was a true soft-lander, comprising a 3-meter-tall vehicle based on a 27-kilogram, thin-walled aluminum triangular structure with one of three legs at each corner and a large solid-propellant retrorocket engine (that comprised over 60 percent of the spacecraft's overall mass) in the center.

The spacecraft was equipped with a Doppler velocity-sensing system that fed information into the spacecraft computer to implement a controllable descent to the surface. Each of the three landing pads also carried aircraft-type shock absorbers and strain gauges to provide data on landing characteristics, important for future Apollo missions.

Surveyor 1, the first in the series, was an unprecedented success. NASA accomplished the first true soft-landing on the Moon on its very first try when the probe landed in the southwest region of the Ocean of Storms at 06:17:36 UT on 2 June 1966, just 63.6 hours after launch from Cape Canaveral. Touchdown coordinates were 2°27' south latitude and 43°13' west longitude, just 14 kilometers from the planned target.

At landing, the spacecraft weighed 294.3 kilograms. The initial panoramic views from the lunar surface indicated that Surveyor 1 was resting in a 100-kilometer-diameter crater that contained boulders of more than one meter in length scattered all around. The photos showed crestlines of low mountains in the distant horizon. The lander transmitted 11,350 images over two separate communications sessions by 6 July.

Although the primary mission was completed by 13 July, NASA maintained contact until 7 January 1967. Without doubt, Surveyor 1 was one of the great successes of NASA's early lunar and interplanetary program.

Key Dates

30 May 1966: Launch (14:41:01 UT)

2 Jun 1966: Lunar Landing (06:17:36 UT)

13 Jul 1966: Primary Mission Complete

7 Jan 1967: Last Contact

Status: Successful

Fast Facts

Surveyor 1 marked the first true soft landing on the Moon.

The landing helped pave the way for Apollo astronauts to safely land on the Moon.

It also transmitted the first American pictures from the surface of the Moon. (Image: Surveyor 1's shadow on the Moon)